Wearable mining lamps mainly provide high-beam condensing illumination, but in the operation with the use of wearable mining lamps, the utilization probability of low beams is over 80%. Since the existing mining lamps are not assisted with suitable low-beam lamps, high-beam lamps are usually used as low-beam lamps for illumination. However, due to the small lighting area and the presence of shadow interference, the illumination is not uniform. As a result, the overall illumination effect during the operation is unsatisfied. Light spots with high illuminance of focused high-beam will cause glaring effect and discomfort in the eyes of user, which negatively influences work efficiency. The improvement in the fining degree of maintenance or operation of equipments put forward higher requirements on close-range illumination. A large lighting area and high illuminance are required, and the lighting area is required to have uniform illuminance, to be free of light spots and shadow interferences, so as to provide a favorable illumination environment for low-beam operation to meet the requirements of close-range observation or operation.
Although some of the existing wearable mining lamps can provide low-beam illumination, yet the low-beam light sources having no lamp cup are just used in case of emergency where the main light source is damaged or at break, they cannot be used for illumination for close-range operation because the light beams are weak and scattered. Although some of the existing wearable mining lamps are equipped with low-beam light sources having lamp cups, yet the lights projected by the reflecting surfaces of the lamp cups of the low-beam light sources are not uniform. In addition, due to the limited space within a wearable mining lamp, it is difficult to design a low-beam light source of a wearable mining lamp in the same way as a low-beam light source of a large-sized, immobile illumination device. Since mining lamps are usually used for underground operations, the requirement on the safety of the lamps is very high. It is required that all electronic elements are sealed inside the housing of the mining lamp, which further increases the difficulty of designing the low-beam illumination of a wearable mining lamp.
Therefore, the low-beam illumination of wearable mining lamps so far has not met the requirements of a large illumination area which has uniform and high brightness and is free of light spots and shadow interferences.
The most common way to wear an explosion-proof mining lamp is to wear it at the front of a safety helmet. According to the needs, it can be worn at any location where it can be conveniently fixed, such as on a shoulder strap or on an arm band. Due to the manufacturing technique and the battery volume, traditional mining lamps have a too large thickness. The joint between the insert and the safety helmet acts as a fulcrum, the gravitational moment generated by the center of gravity of the mining lamp is so large that it causes a feeling that the safety helmet on the head is falling forwards. It is inconvenient for a man wearing it to make any motion and it is laborious for a man to wear it for a long time.
In addition, in order to synchronize the optical axis of the high-beam of the mining lamp with the horizontal sight of a user, in some of the existing wearable mining lamps, the entire lamp cup of the high-beam light source is arranged inside the lamp with forward and downward inclination; in some of the existing wearable mining lamps, the angle of fulcrum at the joint between the insert and the safety helmet is adjusted, in order to increase the angle of forward inclination of a mining lamp worn on a safety helmet; in some of the existing wearable mining lamps, the rear wall is configured to be inclined, so that the mining lamp presents a state of inclining forwards and downwards when it is worn on a safety helmet. Such designs, however, further increase the feeling that the safety helmet is falling forwards when a mining lamp is worn on it.